The thermal decompositions of I-chloro-1-fluoroethane and 1-chloro-1,l-difluorethane at atmospheric pressure have been studied in the temperature range 500-6OO0C in a flow system. The dehydrochlorinations are homogenous in a carbonaceous reactor and unimolecular. The rate constants are given by The criteria for molecular or chain processes in thermal dehydrochlorinations are discussed.

The hydrogen abstraction from asymmetrically fluorinated and chlorofluorinated ethanes by chlorine atoms has been investigated in the gas phase between 264 and 333OK using the competition method. Arrhenius parameters for the reaction on both sites of the molecules are discussed.

The hydrogen abstraction from the chlorinated ethanes by chlorine atoms has been investigated in the liquid phase. Rate constants relative to that for hydrogen abstraction from chloroform have been measured between 2 6 7 O and 333OK using a competition technique. The results are compared with gas-phase data.

T h e rate constants of liquid-phase hydrogen abstraction by chlorine atoms from 1,2-CzH&12 relative to those of addition to CzHClB and to C&14 and to that of hydrogen abstraction from cyclohexane have been measured between 250 and 345°K. Assuming a zero activation energy for the addition reactions permits one to calculate the corresponding values for the liquid-phase hydrogen abstraction from the chlorinated ethanes. These values are discussed and compared with the gas-phase data.

The ratios of rates constants of hydrogen atom abstraction by a chlorine atom from both sites of asymmetrical chloroethanes were measured in the liquid phase at -13 to 40°C. The following values were obtained: Ethyl chloride (in CC14) 1,l-dichloroethane 1,1,2-trichloroethane The results are compared with recent gas phase data and discussed. Experiments in a complexing solvent (CS,) show an increased selectivity compared to the liquid phase due to both enthalpic and entropic effects. k,,,/kz,r = 10°~21*o.10 exp (86f100/RT) kz,*/k2., = 10°~26*o~10 exp (120f 100/RT) kz,t/kz,s = 10-0.09*0.'0 exp (100f lOO/RT)